Re: [PATCH 09/11] PCI: add matching checks for driver_override binding

[Max Gurtovoy]

On 6/9/2021 4:27 AM, Alex Williamson wrote:
> On Tue, 8 Jun 2021 19:45:17 -0300
> Jason Gunthorpe <jgg@xxxxxxxxxx> wrote:
>
> > On Tue, Jun 08, 2021 at 03:26:43PM -0600, Alex Williamson wrote:
> > > > drivers that specifically opt into this feature and the driver now has
> > > > the opportunity to provide a proper match table that indicates what HW
> > > > it can properly support. vfio-pci continues to support everything.
> > > In doing so, this also breaks the new_id method for vfio-pci.
> > Does it? How? The driver_override flag is per match entry not for the
> > entire device so new_id added things will work the same as before as
> > their new match entry's flags will be zero.
> Hmm, that might have been a testing issue; combining driverctl with
> manual new_id testing might have left a driver_override in place.
>   
> > > Sorry, with so many userspace regressions, crippling the
> > > driver_override interface with an assumption of such a narrow focus,
> > > creating a vfio specific match flag, I don't see where this can go.
> > > Thanks,
> > On the other hand it overcomes all the objections from the last go
> > round: how userspace figures out which driver to use with
> > driver_override and integrating the universal driver into the scheme.
> >
> > pci_stub could be delt with by marking it for driver_override like
> > vfio_pci.
> By marking it a "vfio driver override"? :-\

Of course not. We'll mark it as "stub driver override".

> > But driverctl as a general tool working with any module is not really
> > addressable.
> >
> > Is the only issue the blocking of the arbitary binding? That is not a
> > critical peice of this, IIRC
> We can't break userspace, which means new_id and driver_override need
> to work as they do now.  There are scads of driver binding scripts in
> the wild, for vfio-pci and other drivers.  We can't assume such a
> narrow scope.  Thanks,
>
> Alex